The invention pertains to a device for switching a connection, especially an electrical connection in relation to the status of a device to be monitored, especially a safety switch, according to the preamble of claim 1.
Such devices are known, for example, from DE43 28 297 C1. This device has, in a lower housing part, switching means for switching an electrical connection, and in a head part, an opening for inserting the actuator. The actuator turns a switching disk on its rotary axis oriented at a right angle to the insertion direction. Atop the jacket surface of the switching disk is a switching plunger that actuates the switching means and therefore the electrical connection, and which can be held by means of an electromagnet in a position blocking the switching disk and therefore the actuator.
Known from DE43 32 500 A1 is a locking device for monitoring movable protective mechanisms, with two position switches located in the housing and working independently of each other, which can be actuated by means of a switching strip with depressions that passes into and through a housing head.
A safety switch is known from DE196 49 717 A1, the head part of which has two insertion openings, which together determine for the actuator two insertion directions set at a right angle to each other. Depending upon which insertion opening the actuator is inserted into, the switching disk turns in one or the opposite direction. By appropriate means, the switching disk can be fixed in either its starting position or with completely inserted actuator.
Known from DE197 11 588 A1 is a safety switch in which both the actuator and the device have a signal means, by which a contact-free signal transfer can be carried out, which optionally leads to a switching of the electrical connection. The locking of the actuator in the device is accomplished by an engagement by means of magnetic force of an axially displaceable plunger in an opening of the actuator. To determine whether the actuator is inserted and properly locked, both the position of the actuator in the device and the position of the locking plunger must be scanned and linked with a logical AND function.
In the known devices, the actuator must be withdrawn from the device from the same side from where it had been inserted into the device. This results in problems, especially in the monitoring of protective devices of modern machine tools or processing centers with directionally displaceable and partially surrounding sliding windows or sliding doors. These disadvantages are even more significant when, in addition, a locking of the safety device and a monitoring of the lock are required.
It follows that the problem fundamental to the present invention is to make available a device that is universally usable with a multitude of safety devices to be monitored and makes possible a monitorable locking of the device at minimum cost.
The problem is resolved by the device disclosed in claim 1. Special embodiment forms of the invention are disclosed in the subordinate claims.
Due to the fact that the actuator can be withdrawn from the device on a second side, actuators that can be passed through the device are realizable, which, For example, are displaceable in two directions or can be mounted on encircling safety devices. It should be understood that under the first and second sides of the device, there are different, preferably planar, areas delimiting the device. Normally, the device has a housing, which holds the switching element that switches the preferably electrical connection. Via an opening in the housing, the actuator can be inserted or withdrawn. To the extent that the device encompasses a switching disk, the latter is linked to the device or its housing so as to be rotatable by the actuator. The switching disk can then be rotated in both directions, depending upon from which side the actuator is inserted. Both rotary directions can then lead to a switching operation. The head part with the opening(s) for the actuator can be removable from the rest of the housing of the device. Preferably, the head part is open on three sides, while the actuator can be inserted from a first side and can be withdrawn on a second side opposite the first side. Via a third side joining the first and the second sides, the actuator can be secured on the device to be monitored. In this embodiment the head part has a U-shaped cross section. The actuator can also be withdrawn from the device on the third side or be inserted on the third side. The device can also be secured on the device to be monitored, for example, a sliding door or a protective hood, which in this instance is movably affixed in relation to the immovable actuator, for example, on the frame of the device.
Due to the fact that the actuator can be passed through the device, a device designed in this manner can be used in almost all applications, especially for encircling protective devices. Although possible, it is specifically not necessary to withdraw the actuator on the side of the device where it had been inserted into the device.
Since the actuator can be fixed in the device, especially at least partially fixed in form-fit fashion and/or locked, the closed status, For example, of the device to be monitored is arrestable until a machine tool covered by the device has come to a standstill. The release of the locking can ensue manually or automatically once the machine is at a standstill.
Due to the fact that the device includes an actuator receptacle, which can be brought into releasable locking engagement with the actuator, the locking can necessarily take place with each insertion of the actuator. The actuator receptacle and the actuator are especially so designed that they can at least partially be form-fitted together. The locking ensues specifically due to a movement of the actuator transverse to the insertion direction, preferably at an angle of 90xc2x0. As a result, a secure locking effect can be achieved even with weak locking forces. To this end, the actuator is movably linked on the device or the mechanism, especially pivotably linked. Alternatively or supplementally thereto, the actuator receptacle or parts thereof can also be movably designed. Since the weight of the actuator reinforces the locking engagement and preferably effects the locking engagement, additional driving means for the locking movement can be dispensed with. Worthy of consideration as alternative or augmentation is the use of a force accumulator, For example, a compression spring, an electromagnetic drive or a pneumatic propulsion of the actuator, in order to force the actuator into locking engagement and/or to retain the locking engagement.
Inasmuch as the actuator receptacle forms a ramp-like approach surface for the actuator, elevation of the actuator for the subsequent locking engagement in the actuator receptacle can be accomplished without supplemental driving means. A linear or spherical ramp facilitates high processing speeds of the actuator or the protective device with simultaneous secure engagement or locking of the actuator in the actuator receptacle. The ramp is oriented toward all sides, from which the actuator can be inserted into or removed from the device.
By virtue of the fact that the actuator receptacle has a rotatably, and especially a pivotably linked locking element, which can be swung out when the actuator is inserted, it is possible for the actuator to be secured essentially immovably, for example, on the device to be monitored. For instance, the actuator receptacle forms a ramp-like locking element, which, when the actuator is inserted, swings out in such a way that the way is cleared for the actuator to reach the position of locking engagement with the actuator receptacle. As soon as this position is reached by the actuator, the locking element forms a locking surface for the actuator, for example, by pivoting back into its starting position. For loosening the locking engagement, the locking element is again rendered pivotable in such a way that the actuator can be drawn back out of the device.
Since the actuator and the actuator receptacle have signal means working together without contact, additional, especially movable parts inside the device, which serve, for example, to transfer the movement of actuator to a switching plunger, can be dispensed with. Of course, the electrical connection to be switched can still be contact-switched, for example, by means of a relay addressed by the signal means. The preferably electronic signal means also permits by way of an appropriate coding a clear identification of the actuator. The signal transfer is not contact burdened and takes place especially wirelessly, for example, optically or by radio. The paired signal means can be configured in various ways.
For example, only one of the two signal means, preferably that secured on the device, can send out a signal or information, and the other signal means provides essentially a complete or partial reflection of the emitted signal. Alternatively, the other signal means can receive the emitted signal and send it back to a signal means unchanged or individually altered. Here analog and/or digital signals can be transmitted in one or both directions. Preferably, one of the signal means, especially that secured on the device, also provides the power for the operation of the other signal means, preferably in the form of electromagnetic radiation in the visible or invisible frequency range.
Inasmuch as a signal transfer is only possible when the actuator is irremovably locked in the device, i.e., when the actuator and the actuator receptacle are in locked engagement, an additional locking of the actuator and especially an additional query of the position of the locking plunger, as well as the AND function with the query of the position of the actuator, can be dispensed with. In the locking engagement of the actuator and the actuator receptacle, the first and the second signal means are directly opposite each other. In particular, they can be located on opposing locking surfaces. Preferably, the second signal means located in the actuator receptacle is so arranged and set back from the surface of the actuator receptacle facing the actuator that the electromagnetic radiation emitted by it has a directional characteristic toward the position of the first signal means of the actuator in the status of the locking engagement. Security against an erroneous closure is thereby ensured, i.e., a signal transfer between the two signal means is precluded, despite the fact that the actuator is still not in locking engagement with the actuator receptacle.
By virtue of the fact that the device can be operated only with the provided actuator for switching the connection, a manipulation safety is ensured for the device. This can take place especially because the device has a narrow and/or deep slit for guiding the actuator through, which makes the actuator receptacle inaccessible from the outside at least to the extent that the device cannot be made to switch with a means not provided for switching said means and/or that the actuator in engagement with the actuator receptacle is releasable from this engagement. This is realizable, for example, with a flat slit open on three sides and U-shaped in cross section, through which the actuator can be guided from a first to the oppositely located side. The manipulation safety is enhanced by the use of first and second signal means, which makes possible a clear identification of the actuator, For example, by means of a code word stored in the first signal means of the actuator, and switches the connection only with commensurate identification.
Insofar as the device for loosening the locking of the actuator encompasses unlocking means, the unlocking can occur automatically. Especially acceptable are electromagnetic or pneumatically driven ejectors, a force accumulator in the form of a spring or a compressed-air nozzle, depending upon whether the locking of the actuator in the actuator receptacle is accomplished by spring force or magnetic force or simply by gravity.